开发小计

把某一列的数据全部查出来，又不重复某一列

SELECT cat_id, group_concat( goods_name )  sn//group_concat( goods_name )  as  sn,as一般省略
FROM ecs_goods
GROUP BY cat_id DESC

distinct ,只能在最前面，只有后面的所有列重复，才显示一条

group by 例子:select count(sno) sn,sno from tablename group by sno